Design of novel bio-gated nanomaterials for sensing and therapeutic applications

Resumen

The present PhD thesis, entitled "Design of novel bio-gated nanomaterials for sensing and therapeutic applications", is focused on the design, preparation, characterization and evaluation of new smart hybrid organic-inorganic materials for their applications on the field of sensing and controlled drug delivery. The first chapter of this thesis introduces the concept of organic-inorganic hybrid materials containing switchable "gate-like" ensembles and their applications in the detection of chemical and biochemical species and as suitable materials for drug delivery applications. The second chapter describes the preparation of an aptamer-capped mesoporous material for the fluorogenic detection of thrombin in human plasma and serum. For the preparation of the material dye-loaded MCM-41 particles were capped with a thrombin aptamer (TBA). In the presence of thrombin, TBA was displaced from the surface due to the formation of TBA-protein complex, triggering the release of the dye. The capped system was tested in simulated human blood plasma and in PBS buffer with 10% of human serum and achieved a low limit of detection (LOD) for thrombin. Moreover, the prepared material displayed great selectivity for thrombin in the presence of other non-exclusive binding proteins. The gated-nanomaterial resulted suitable to perform an accurate thrombin detection in human serum. In the third chapter a new fluorogenic sensing nanoprobe for the detection of As(III) is described. The system consists of the combination of MSNs with an aptamer (Ars-3), which possesses a very high affinity to As(III), as a pore blocking agent. The sensitivity of the nanocarrier for As(III) was further studied. Furthermore, the selectivity of the nanocarrier towards As(III) in the presence of other cations was also successfully verified. In addition, the sensor allowed accurate As(III) determination in real media. The fourth chapter reports a novel proof-of-concept to detect Mycoplasma genomic DNA and cocaine. The new approach combined gated mesoporous silica nanoparticles and surface-enhanced Raman scattering (SERS) spectroscopy. In particular, two gated-hybrid mesoporous materials loaded with a SERS reporter and capped with suitable oligonucleotide sequences to detect Mycoplasma genomic DNA or cocaine, were prepared. Release of the reporter was triggered from the different materials by the presence of the corresponding target, and was detected by SERS upon adsorption on gold nanotriangles. This novel procedure allowed detecting Mycoplasma genomic DNA and cocaine with a high selectivity and sensitivity. The fifth chapter describes the development of a nanodevice able to deliver insulin as a function of the glucose concentration, in simulated human blood plasma. The glucose-driven nanomaterial consisted of ß-cyclodextrin-modified glucose oxidase (CD-GOx)-capped silica nanoparticles loaded with insulin. The reaction of glucose by the capping enzyme (GOx) triggered insulin release in a self-regulated manner. Furthermore, the response to glucose was found to be selective and other saccharides were unable to deliver the entrapped insulin. We hope the results obtained in this thesis may inspire further works to design smart nanodevices with application in analytical chemistry, clinical or environmental assays and self-regulated drug delivery systems.